Painter of wildlife and the countryside, commercial artist and teacher, who aged 12 sold his first painting, A Prairie Falcon, to the milkman for £5. In 1966, he joined Phoenix Studios as a trainee illustrator and attended the London School of Printing, the year following sailing around the world as a merchant seaman. On return, Armstrong worked as a commercial artist, had a first solo exhibition in Bromley which sold out at the preview, then in 1970 moved to Devon and began painting full-time. Armstrong taught art at Okehampton Comprehensive, 1971, part-time at Exeter College of Art, 1975, and was artist-in-residence at the National Marine Aquarium, Plymouth, 1998–9. In 1977, Armstrong joined South West Water as a river warden; he also made global field trips and joined an Arctic expedition.